1. Field of Invention
This invention relates to the field of reinforcing vehicles to lessen roof crush during rollover. More specifically, this invention relates to a reinforcement that can be deployed during a vehicle rollover to cooperate with the vehicle roof to lessen roof crush during the rollover.
2. Background
United States Federal Motor Vehicle Safety Standard (FMVSS) 216 is a requirement designed to protect vehicle occupants in the event of a rollover accident. New standards require that, by 2009, roof deformation be limited to five inches (127 mm) of crush. Under the new standard, a vehicle's roof structure will have to support 2.5 times the vehicle weight or 5,000 pounds, whichever is less (up from the previous requirement of 1.5 times the vehicle weight).
Presently, most non-convertible automobiles have pillared hardtops. A pillared hardtop typically includes a framework of A-pillars, B-pillars, C-pillars, and interconnecting roof rails and headers. This framework protects vehicle occupants should a rollover condition occur, by limiting roof crush. The A-pillars are typically located on the sides of the vehicle's front windshield. The C-pillars are typically located on the sides of the vehicle's rear window. The B-pillars are typically located about midway between the A-pillars and the C-pillars. The roof rails and headers extend between the pillars longitudinally and transversely.
To strengthen roof structures to meet the new requirements, there are a number of alternatives that are commonly used. The most common practice to strengthen the roof structure is to increase the strength of the A-pillar, B-pillar, and C-pillar, as well as the roof rails and headers. Strengthening these elements is most commonly achieved by increasing their size and thickness, which can increase vehicle weight and production costs. Other ways to strengthen these elements include using stronger materials, which may be prohibitively expensive to obtain or use in existing production facilities, and adding additional support elements, which also increases vehicle weight and production costs.
It has been proposed, in convertible vehicles that do not have protective roof structures, to employ rollover bars that are enclosed within or otherwise attached to a vehicle's seat. The rollover bars are activated, upon sensing a rollover condition, to extend upward to protect the seat occupant during rollover. These rollover bars are disclosed to be desirable due to the lack of a protective roof structure in convertible vehicles, and are not adapted or designed to work in cooperation with a pillared hard top to reinforce the pillared hard top.